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- Author or Editor: P. Rajec x
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Abstract
64Cu (T1/2 = 12,7 h, β− 37,1 %, β+ 17,9 %, EC 41 %) is a useful radioisotopes for positron emission tomography radiopharmaceutical. We used the reaction route 64Ni(p,n)64Cu for the 64Cu preparation. A basic disadvantage of this route, a high price of the enriched target material, was eliminated by using very simple recycling procedure. Compact solid target irradiation system was installed at the end of the external beam line of the IBA Cyclone 18/9 cyclotron. In this paper, the irradiation of 64Ni target and separation of 64Cu from a target material is described. The separation was achieved by anion exchange chromatography with HCl as a elution solution. The distribution ratio for different HCl concentrations on Bio-Rad AG1-X8 and elution profile of 64Cu were investigated. 64Cu production rate for 100 mg 64Ni of 99.09 % purity (ISOFLEX) on gold target was 104 MBq/μAh. The activity of the product was checked by ionisation chamber (Curiementor), gamma spectrometry using a HPGe detector and liquid scintillation counting using the triple-to-double coincidence ratio method. The separation process of 64Cu was made in a home-made separation module.
Abstract
An on-column radiometric detector for capillary isotachophoresis is described. Design of the detector follows its intended use, i.e., mainly the detection of14C labelled ionogenic compounds separable by this electromigration method. A key part of the detector is a small volume (70 or 200 nl) cell with the sensing part made of plastic scintillator with counting efficiencies of 13–15%. An equation correlating the precision of radioactivity measurements with physical and geometrical characteristics of the cell and isotachophoretic conditions has been derived providing a guide in optimizing both the geometrical dimensions of the cell and the isotachophoretic working conditions. A minimum detectability calculated for14C radionuclide (21 Bq for a 3 mm thickness of the sensing part of the cell) was in a good agreement with the value determined experimentally (16 Bq). Other parameters evaluated experimentally include resolving power, short- and long-term reproducibilities of the response. It was also shown that optimized driving current during the detection enables to improve the precision of the radioactivity measurement.
Determination of plutonium-239,240 in environmental samples from surroundings of the Atomic Power Station Jaslovské Bohunice
Determination of plutonium in Manivier and Dudváh river
Abstract
Specific activity of239,240Pu in contaminated soils from the bank of Manivier channel was determined to be in the range of 5–40 Bq·kg–1 and for soils from the bank of Dudvah river 0.6–8 Bq·kg–1. The ratio of239,240Pu/137Cs found in the samples is about 1·10–4, which is very close to the ratio found in the pulp of high activity concentrate in the collecting tank of nuclear power plants (NPP).
Abstract
The reaction route 64Ni(p,n)64Cu is very popular for the preparation of 64Cu because its entrance channel is accessible at low energies and yield of reaction is quite high. However, a high price of the enriched 64Ni is a disadvantage of this reaction path; hence, preparation of a chemically pure nickel targets for the production of 64Cu using COSTIS (Compact Solid Target Irradiation System) is of a great research interest. In this paper, effects of boric acid, composition of electrolytic bath and electrochemical process conditions on the quality of nickel films deposited on 2 mm thick gold or platinum disc targets were investigated. Chemical purity of the electrodeposited nickel was measured by the Auger electron spectroscopy and the surface quality of targets was studied microscopically (SEM). A SRIM program was used for a thickness target calculation. COSTIS target station was installed at the end of the external beam line of the IBA Cyclone 18/9 cyclotron, and the irradiation surface of target was optimized. The target station has been equipped with Al or Nb window foil in the front of the target to degrade the beam energy to an optimal value.
Abstract
Radiolytical decomposition of phenol was investigated at60Co gamma irradiation (1–2 Gy·s–1, 
10 kGy) of pre- and continuously aerated aqueous solutions at concentrations of phenol 1–100 mg· ·dm–3 and in the presence of sodium hydroxide, sulphuric acid, sodium and ferrous sulphate, formaldehyde, 2-propanol,n-hexane, xylene, benzene, and commercial gasoline. From the decomposition rate at doses 50–400 Gy, a phenomenological model of linear relation between the dose acquired for 37% decomposition (D
37), initial concentration (g·m–3) of phenol (p
0) and of an admixture (s
0) was confirmed in the formD
37=52f
tr(p
0+f
eq
s
0), wheref's are constants which can be attributed to the relative transformation resistance of phenol towards the OH radicals in given matrix (f
tr, for pure waterf
tr=1) and relative acceptor capacity of competing substrate (f
eq). In real wastewaters, the efficient decrease of phenols content may be substantially lower than that in model solutions, obviously due to radiation oxidation of aromates, as proved by irradiation of aqueous solutions of benzene. Technical and economical feasibility of the process is discussed.
Abstract
The physical and chemical properties of illitic clay minerals from Slovak deposit suitable for application in engineering barriers for high level radioactive waste repositories and spent nuclear fuels were studied. The isolation of spent nuclear fuels and high level radioactive wastes from the outer environment in a deep repository is gained by means of a system of multiple engineering and natural sealing barriers. Vital segments in a multiple barrier system are clay rocks, of which bentonites represent the most suitable clay material. Cs-adsorption on fine fractions of adsorbents (bentonites from three Slovak deposits: Jelšový potok J15, Kopernica K15, Lieskovec L15 and montmorillonite K10) has been studied with using batch of radiometric techniques. Adsorption parameters have been determined for adsorbent-cesium solution system as a function of contact time and adsorbate concentration. The influences of pH change, the effect of competitive cations, complex-forming organic chelating agents on the adsorption of Cs have also been studied.
Abstract
Bentonites which are characterized by good rheological, mineralogical and chemical stability is considered used as sealing barriers in multibarrier Slovak system of deep geological repository for high-level radioactive waste and spent nuclear fuel. In Slovak Republic there are several significant deposits of bentonite, which are characterized by appropriate adsorption properties and meet the geotechnical requirements for this type of barriers. Study of adsorption properties of bentonites and other smectites is an essential step for developing the migration model long-lived corrosion and activation products, and fission products of uranium. Nuclear wastes contain the most important nuclear fission products, radioisotopes 134Cs and 137Cs. The present paper investigates and compares the cesium adsorption properties of Slovak and North America bentonites composed mainly of dioctahedral smectite montmorillonite (J, L, SAz-1 and STx-1) and trioctahedral smectites saponite (SapCa-2) and hectorite (SHCa-1).
Abstract
One of the basic prerequisites for the use of bentonite as engineering barrier in deep geological repositories for radioactive waste and spent nuclear fuel is their stability against ionizing radiation stemming from radionuclides present in radioactive waste and spent nuclear fuel. The aim of this study was to compare the changes in the adsorption properties of selected Slovak bentonites in relation to uranium fission products (137Cs and 90Sr), prior to and after irradiation of bentonites with a 60Co γ-source and specifying the changes in the structure of Slovak bentonites induced by γ-radiation. The changes in irradiated natural forms of Slovak bentonites and the changes in their natrified analogues and fractions with different grain sizes were studied from five Slovak deposits: Jelšový potok, Kopernica, Lastovce, Lieskovec and Dolná Ves. The EPR spectra of bentonites from deposits Jelšový potok and Lieskovec with absorbed doses of 104 and 105 Gy γ-rays showed no changes in the structure of the studied Slovak bentonites. The changes, which in terms of structure destabilization can be considered insignificant, occurred only in bentonites with absorbed doses of γ-radiation as much as 1 MGy. The absorbed dose of 1 MGy γ-radiation did not have an effect on the adsorption of cesium on every studied bentonite. Changes that can also be regarded as insignificant occurred only during strontium adsorption, especially on Fe–bentonite from deposit Lieskovec and Ca–Mg–bentonite from deposit Jelšový potok, when an increase in the adsorption capacity occurred. Attention should be paid in further research of this topic which would require carrying out experiments on bentonite samples with absorbed doses higher by several orders of magnitude.
